The defects of the tin bronze plate are mainly manifested in the unreasonable design of the casting structure, sharp corners, and the wall thickness of the casting is too wide; the sand mold (core) has poor concession; the mold is locally overheated; the pouring temperature is too high; the casting is taken out of the mold Too early; the heat treatment is overheated or burned, and the cooling rate is excessive.
Prevention of defects in tin-bronze plate castings: Improve the structural design of the castings, avoid sharp corners, strive for uniform wall thickness, and smooth transition; take measures to increase the sand mold (core) concession; ensure that all parts of the casting are solidified at the same time or sequentially, and improve pouring System design; appropriately reduce the pouring temperature; control the cooling time of the mold; use the thermal correction method when the casting is deformed; correctly control the heat treatment temperature and reduce the quenching cooling rate.
After the tin-bronze crankshaft is bent and deformed, eccentric wear occurs on the working surface of the cylinder, the small end of the connecting rod copper sleeve and the connecting rod bush are overheated and early wear of the bearing steel sleeve, and the crank is ground into a cone shape. Therefore, in the overhaul or middle repair of the compressor, the bending of the crankshaft should be checked in order to find out and take corresponding measures as soon as possible to avoid greater damage to the copper bushing of the agricultural machinery. Before inspection, the crankshaft needs to be scrubbed clean and placed on the "V"-shaped frame of the inspection platform, or the center holes at both ends of the crankshaft should be pushed on the lathe with a thimble, and then the dial indicator should be used for inspection.
When inspecting, align the dial indicator at the measuring point with one or two main journals in the middle of the crankshaft. After slowly turning the crankshaft one circle by hand, the pendulum indicated on the dial indicator is the bending pendulum of the crankshaft. The results of the copper sleeve of the cylinder earrings measured in this way may also have a large error, because it also involves the out-of-round condition of the two main journals supported on the "V" frame and the middle main journal. Look at the crankshaft Whether the bending oscillating difference of the crankshaft has any influence; if it does, the flexural oscillating difference of the crankshaft should be adjusted according to the situation.
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